Treatment of formates of metals of the alkali-earth group



Patented 7 Mar. 29, 1927.

UNITED STATES 1,622,991 PATENT OFFICE.

o'r'ro PAUL cunr 31mm, or ALLnN'rowN, PENNSYLVANIA, AssIGNon r TROJAN POWDER COMPANY, or NEW YORK, N. Y., A CORPORATION 01 NEW YORK.

TREATMENT OF FORMATES 0F METAL 01 THE ALKALI-EABTK GROUP.

No Drawing. Application filed April 7, 1921, Serial No. 458,500. Renewed January 12, 1924.

My invention relates to the treatment of formates of the alkali earth group, and more particularly to the preparation of oxalic acid from such formates.

5 It is well known that when formates are heated, a more or less complete transformation to oxalates may be obtained. The preparation of sodium oxalate from sodium formate by regulated heating has long been practiced on a large commercial scale, and today forms the basis of the synthetic oxalic acid industry.

When calcium form-ate, or the formate of any of the other alkali earth metals, .is

a of oxalate is much less complete than when sodium formate is similarly treated.

I have discovered a convenient and cheap means by which the formates of alkali earth metals may be treated-for the preparation therefrom of oxalic acid, with much better yields than those which could be obtained by hitherto known methods.

As an illustration of my invention I will 1 se arate'the calcium hydroxide-"from the solu 1e sodium formate, and dry the sodium sodium oxalate.

action with-my precipitated sludge ofcaldium hydroxide, at which a reaction occurs with the formation of sodium hydroxide and the precipitation of calcium oxalate.

The calcium oxalate is of course capable of conversion into oxalic acid by treatment with sulfuric acid. in the usual way.

It will be noted that by my invention calcium formats "is cpnverted into calcium oxafresh material to replace the small amount treated in asimilar manner, the production form sodium formate-and calciumhydroxide,

formats and convert it in the .usual way to I next bring this sodium oxalate into relate indirectly, and without the losses in yield which occur when the direct transfor-- mation is attempted. Each of the reactions goes on readily with high or practically quantitative yields. In the first stageof my reaction I use sodium hydroxide and obtain calcium hydroxide, and in the second i'stage of my reaction I use calcium hydroxide and obtainsodium hydroxide. As a result no reagents are employed in my process be, yond the quantity used in the treatment of the first batch, and the addition of suflicient lost in the wash-waters.

Although my present procedure involves three steps, as compared with the single step of heating calcium formate to prepare calcium oxalate therefrom, yet 'aseach of the three steps which I use involves very'small losses, the result obtained by the use of the three steps is more economical and desirable than theuse of the single step procedure as at present practiced.

I claim: y y

1. A process comprising reacting upon calcium 'formate with sodium hydroxide to form sodium formats, heating the sodium formate to obtain sodium oxalate, and causing the sodium oxalate to react with calcium hydroxide to form calcium oxalate and sodium hydroxide- '2. A process. comprising reacting upon calcium formate with sodium hydroxide to transformin the sodium formate to sodium oxalate, an bringing about a reaction between the sodium oxalate and the calcium hydroxide resulting from the first reaction to form calcium oxalate, andregenerate sodium hydroxide.

3. A continuousprocess for. the prepara- 1 tion of oxalates. from. calcium formats, 1 which consists in treating the calcium for mate with sodium hydroxide to form formats and calciumhydroxide, converting the sodium formate to sodiuin oxalate, causing reaction between the sodium oxalate and calcium hydroxide to form calcium oxalate and sodium. hydroxide, removing the calciumcxalate and supplying fresh, calcium formate for reaction with the regenerated sodium hydroxide and the succeeding treatment-as described. I

4. In the treatment of calcium formats n to produce oxalates theregim, the step of 1 transforming calcium formate info sodium s dium hydroxide to form sodium fo'rinaln format-o. v i and iho hydroxide of said iuoizil. irausi'oriu 5. In the process of pl'miuving oxalalon ing the sodium formulo to sodium n'xzilulv, from calcium formulo, tho slop which cow and rem-ting upon the @odium oxulnh- \\'iii| sists in treating calcium formats with lhe hydroxide of the alkali oul'ih nu-lul rosodium hydroxide in form sodium formato Suliing from the first rom'liou lo i'orm ilu' and calcium hydroxide. oxalate of tho-said metal and i'rginoi'nlc 6. A process comprising reacting upon sodium h \'dr0xido. ih formate of an alkali earth metal with OTTO PAUL (Ull'l BRIGHT 

